Fuel injection system



April 6, 1937. J. R. LEMON 2,075,949

FUEL INJECTION SYSTEM Filed Nov. 15, 1955 a? 13 Pals?! 29 a8 14 aINVENTOR.

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L65./a" FUEL msssulee Jbsg h/ Tc. Lamom Patented Apr. 6, 1937 FUELINJECTION SYSTEM Joseph R. Lemon, Detroit, Mich assignor to Ex- Cell-OAircraft & Tool Corporation, Detroit, Mich., a. corporation of MichiganApplication November 15, 1933, Serial No. 698,082

11 Claims.

The present invention relates to improvements in fuel injection systems,and has particular reference to a new and improved hydraulicallyoperable injection nozzle.

One of the primary features of the invention resides in the provision ofa new and improved nozzle having a valve adapted to be opened and closedby the pressure of the fuel, and in which the fuel for operating thevalve is supplied through 10 a single line.

A further object is to provide a nozzle of the foregoing character inwhich the single line also supplies the fuel for injection.

Further objects and advantages will become apparent as the descriptionproceeds.

In the accompanying drawing, Figure 1 is a fragmentary verticalsectional view through a cyllnder and combustion chamber of an internalcombustion engine with a fuel injection nozzle embodying the features ofmy invention mounted in operative position.

Fig. 2 is a plan view of the nozzle.

Fig. 3 is a longitudinal sectional view of the nozzle takensubstantially along line 3-3 of Fig. 4.

Figs. 4 and 5 are transverse sectional views taken respectively alonglines 4-4 and 5-5 of Fig. 3; I

Fig. 6 is a diagram illustrating the operation of the nozzle.

30 Fig. 7 is a view similar to Fig. 3 but of a modified form of nozzle.

While the invention is susceptible of various modifications andalternative constructions, I have shown in the drawing and will hereindescribe in detail the preferred embodiment, but it is to be understoodthat I do not thereby intend to limit the invention to the specific formdisclosed, but intend to cover all modifications and alternativeconstructions falling within the spirit 4 and scope of the invention asexpressed in the appended claims.

Referring more particularly to the drawing,

the fuel injection system may comprise any suitable number of dischargenozzles depending in part on the number of engine cylinders to be 50stance, a single nozzle 1 is shown mounted to discharge into acombustion chamber 8 in communication with the head end of an enginecylinder 9 in which a piston I0 is reciprocable, and is adapted to beoperated periodically in timed rela- 55 tion to the reciprocation of thepiston.

The nozzle 1, in its preferred form, has a, sectional body comprising aholder II and a discharge tip I2, which may be provided in any suitableshape, and which in the present instance are generally cylindrical andin endwise engagement. Preferably, the adjacent ends of the holder IIand the tip I2 have flat and smoothly lapped contacting faces I3 and I4-affording a pressure tight joint. A flanged nut I5, engaging aperipheral shoulder I6 on the discharge tip I2, is threaded onto theadjacent end of the holder II to secure 10 the parts tightly inassembled relation. The nozzle I is mounted in position, with thedischarge tip I2 extending through an opening I! in one wall of thecombustion chamber 8, by means of two diametrically opposed lugs I8 onthe nut I5 which are rigidly secured to the head of the cylinder 9 bybolts I9.

The discharge tip I2 is formed with a fuel chamber 29, and may beprovided with any suit? able number of injection orifices opening to thecombustion chamber 8, and adapted to be'connected by fuel pressureoperable valves to the fuel chamber. In the present instance, the nozzleI is shown with a single orifice 2| controlled by a valve 22. v

The valve 22, in its preferred form, comprises aconical seat 23 locatedbetween the fuel chamber and the orifice 2 I, and a coacting valvemember 24 operable by a reciprocable plunger 25. The

plunger 25 is disposed in a bore 26 which opens axially through thedischarge tip I2 from the inner face I4 to the fuel chamber 20, and theinner end of which defines a control chamber 21 adapted to contain fuelunder pressure. In the operation of the valve 22, the face I3 limits theextent of movement of the plunger 25, and hence determines the degree ofvalve opening. A dif-' ferent degree of valve opening can be obtained bysubstituting a plunger 25 of a different length. 40 The inner end of theplunger 25 defines a face or area 28 exposed to the pressure in thechamber 21 and acting in a direction to seat the valve member 24. Theother end of the plunger 25 is reduced in size to define an annular faceor area 29 exposed to the pressure in the fuel chamber 20 and acting ina direction to lift the valve member 24. When the valve 2I is open, theend face of the valvemember 24 also is exposed to the pressure in thefuel chamber 20, and acts in a direction to hold the valve open. Thetotal effective area of the valve face and the lifting face 29substantially equals that of the seating face 28. Reciprocation of theplunger 25 is effected by relatively varying the pressures in thechambers 5 20 and 21, i. e., by reversing the pressure differentialacting on the faces 28 and 29-24.

One of the important features of the present invention resides insupplying the fuel for both 5 chambers 20 and 21, and for effectingpressure fluctuations therein to operate the valve 22, through themedium of a single fuel supply line 30 connected to the nozzle 1. In thepresent in-- stance, the fuel supply line 39 is in constant comlOmunication with a passage 3| formed in the holder H, and opening to thecontrol chamber 21. Fuel under pressure for injection and to exert alifting force on the plunger 20 is supplied to the chamber 20 from thechamber 21 through a restricted leakage path of high resistance. Thispath may be provided in various ways. Thus, the plunger 25 may have aloose fit in the bore25 so that the annular clearance therebetween willdefine the connecting path, as shown in Fig. '7, wherein this clearanceis made to appear on a somewhat larger. scale than other parts of thenozzle so as to facilitate illustration thereof. Preferably, however,the path consists of an axial bore 32 opening from the face |4 into theplunger 25, and communicating at its inner or closed end through arestricted orifice or port 33 with the chamber 20. Where a plurality ofnozzles 1, or a plurality of plungers 25 for a series of orifices 2| ina single nozzle, are provided, the leakage paths for the respectiveplungers may be provided in different ways.

In the operation of the engine, the injection is timed to occur over apredetermined period, variable in duration for example from 0 to ofcrank shaft rotation. The pressure fluctuations for effecting operationof the nozzle 1 in timed relation to the reciprocation of the piston l0are illustrated in Fig. 6, wherein fuel pressures in pounds per squareinch are plotted along the ordinate and degrees of crank shaft travelare indicated along the abscissa. Between successive periods ofinjection, the valve 22' is closed, and fuel under a maximum pressure of5000 pounds per square inch is directed through the line 30 4 andpassage 3| to the control chamber 21 as represented by the line AB. Fuelleaking through the bore 32 and the restricted port 33 in Fig. 3 oralong the peripheral surface of the plunger 25 in Fig. '1 graduallybuilds up an equal pressure in the fuel'chamber 20. However, the valve22 remains closed since the area of the face 29 is less than that of theface 28. The ratio of these areas is such that upon a reduction in theseating pressure acting on the face 28 to below a predetermined point,for example 3,750

pounds per square inch, while substantially maintaining the highpressure in the chamber 29, the valve 22 will open. At the point B,representing approximately top dead center of the piston lo,

a sudden pressure reduction of approximately 40 per cent. along lineB.CD to a pressure of 3,000 pounds per square inch is instituted in thechamber 21. The restricted port 33 in Fig. 3 or peripheral clearancebetween the plunger 25 and the bore 26 in Fig. '1 prevents acorresponding drop in pressure in the chamber 20, and hence the valvemember 24 is lifted to start injection at the pointC, representingapproximately one and one-half degrees of crank shaft rotation past topdead center. Fuel stored 'in the chamber 20 is thereupon injectedthrough the orifice 2| into the combustion chamber 8. The duration ofinjection is dependent on the duration of pres- I sure reduction in thechamber 21, and may be varied in accordance with the engine operatingrequirements. For full load operation, the pressureis maintained at3,000 pounds per square inch along the line DE, and is then restoredsuddenly to the initial high pressure along the line E-F. Duringinjection, a slight local pressure drop occurs in the fuel chamber 20adjacent the lifting areas 29 and 24. @Hence, upon restoration of theseating pressure in the chamber 21, the valve 22 is closed. For small oridling loads,

the seating pressure may be restored immediately along the line DG. Uponclosing of the valve 22, the fuel in the chamber 20 is replenished inpreparation for the next cycle. 4 I

It will be evident that the pressures 'in the chambers 20 and21tendslowly. toequalize due to the connecting passage32 33 or theperiph-. eral clearance in Flgi'i'Tl However, becausefof the relativelyshort duration of the m etio'n period, 1 and the restrictedig'character.iof gth'ei iintercommunication between 'the" chambers,gsuch-equalization does notoccurduring'the iniection period, and hencethe injection-pressure does'not drop appreciably. On the other hand, theidle period continues during most of the crank shaft travel, and affordsadequate time for restoration of the fuel supply in the fuel chamber 20for the next injection.

The fuel chamber 20 preferably has a relatively large pressure storagecapacity so that the injection pressure will remain practicallyconstant.

This pressure storage capacity may be obtained in various ways, forexample by providing a large confined space,'defined by the chamber 25alone or with a supplemental space open thereto, and/or by providing aconfined space with resilient walls, adapted for directcommunicationthrough the valve 22 with the orifice 2|. Where a pluralityof nozzles 1 are employed, the desiredpressure storage capacity maybeobtained by interconnecting the various fuel chambers. In the presentinstance, the desired pressure storage capacity is obtained by means ofa reservoir or accumulator chamber 34 in direct and unrestrictedcommunication with the chamber 29, and in effect forming a part thereof.The chamber 34 is defined by a cylindrical shell 35 of slightlyresilient material, suchas seamless steel tubing, closed at one end bythe holder H, and at the other end by a head or closure member 35. Acentral tube 31 extends axially through the chamber 34, and at one endisseated in a recess 33 in the holder II in direct communication with thepassage 3|, and atthe other end extends outwardly through an axialsleeve 39 integral with the member 35. The discharge end of the supplyline 30 is removably secured, as by a nut 49, to the outer end of thesleeve 39 in direct communication with the outer end of the tube 31.Preferably, the holder theshell 35, the closure vmember 35 and the tube31 are tightly and perbility of the fuel, a 'large pressure storagecapacity is obtained which serves to maintain the in timed sequence.

65 valve member movable with 5 1 is effected solely by pressurefluctuation in the single control and fuel supply line 30. When aplurality of nozzles l are provided for the cylinders of amulti-cylinder engine, the pressure fluctuations in the respective linesare effected Any suitable means (not shown), such for example as anadaptation of the fuel distributor disclosed in said copendingapplication, may be provided to supply the fuel under pressure and toeffect the desired pressure 15 control.

I claim as my invention:

1. A unitary fuel injection nozzle comprising, in combination, a bodyhaving a valve chamber with an outlet opening from said seat, a pressurestorage space within said body and having a resilient wall and being inopen communication with" said valve chamber, a control chamber, and abore connecting said chambers, a plunger reciprocable in said bore andhaving oppositely acting pressure faces exposed respectively in saidchambers, one of said faces being formed with a valve member adapted tocoact with said seat, means for supplying fuel under pressure to saidcontrol chamber, and a restricted leakage path located within theconfines of said bore longitudinally of said plunger and independent ofsaid space and establishing a direct constant intercommunication betweensaid valve chamber and said means for permitting a gradual flow of fuelon occasion to said valve chamber.

2. A fuel injection nozzle comprising, in combination, a body having avalve chamber with an outlet valve seat, a discharge passage opening 40from said seat, a control chamber, and a bore connecting said chambers,a plunger reciprocablc in said bore and having oppositely actingpressure faces exposed respectively in said chambers, one of said facesbeing formed with a valve member adapted to coact with said seat, saidplunger being substantially smaller in diameter than said bore to definea restricted leakage path between said chambers adapted to permit agradual equalization of the pressures therein, and means for supplyingfuel under pressure to said control chamber, whereby predeterminedpressure fiuctuations in opposite directions in said means will causesaid valve member. to move respectively into and out of engagement withsaid seat.

3. A fuel injection nozzle comprising, in combination, a body having avalve chamber with an outlet valve seat, a discharge passage openingfrom said seat, a control chamber, and a bore connecting said chambers,a plunger reciprocable in said bore and having oppositely actingpressure faces exposed respectively in said chambers, the area of thepressure face exposed in said control chamber being as large as that ofthe pressure face exposed in said valve chamber, a said plunger andadapted to coact with said seat, said plunger being formed with apassage open at one end to said control chamber and with a restrictedleakage orifice connecting the other end of said passage to said valvechamber, and passage means for supplying fuel under pressure to saidcontrol chamber, whereby predetermined pressure fluctuations in oppositedirections in said means will cause said valve member to moverespectively into and out of engagement with said seat.

stricted passage open at one valve seat, a discharge passage 4. A fuelinjection nozzle comprising, in combination, a body having a valvechamber of relatively large storage capacity with an outlet valve seat,a discharge passage opening from said'seat, a control chamber ofrelatively small capacity, and a bore connecting said chambers, aplunger reciprocable in said bore and having oppositely acting pressurefaces exposed respectively in. said chambers, one of said faces beingformed with a valve member adapted to coact with said seat and v beingequal in effective area tothe other of said faces when said member islifted and less in effective area than said other face when saidmemb'eris seated, said plunger being formed with a reend to said controlchamber and at the otherend'to said valve cham-' ber, and means forsupplying fuel under pressure to said pressure chamber, wherebyequal-pressures in said chambers will cause said valve member tov beseated and a sudden pressure drop in said control chamber will effectmember.

5. A fuel injectionnozzle comprisingfln combination, a body having aconfined chamber and a control chamber, a reversibly movable pressureresponsive element interposedbetween and having pressure faces atopposite sides exposed respectively to said chambers, the area of thepressure face exposed in said control chamber being as large as that ofthe pressure face'expos'ed in said confined chamber, an injection valveoperable by said element, a restricted leakage passage formed in saidelement and establishing intercommunication between said chambers, andmeans for supplying fuel under pressure to said lifting of said valvecontrol chamber, said confined chamber being adapted to receive fuelfrom said control chamber only through said restricted passage.

6. A fuel injection nozzle comprising, in combination, a body section, acylindrical shell mounted on one end of said section and defining aconfined reservoir chamber, a discharge tip mounted on the other end ofsaid'section and formed with a valve chamber and a control chamber andwith a discharge passage opening from said valve chamber, a valve forcontrolling said passage, means connecting said reservoir chamber andsaid valve chamber, a pressure responsive member exposed at oppositesides to said valve and control chambers, a restrictedleakage path"connecting said valve and control chambers, a tube extending throughsaid reservoir chamber and opening to said control chamber, and a fuelsupply conduit connected to said tube.

7. A fuel injection nozzle comprising, in combination, a body having avalve chamber and'a control chamber, an element reciprocable in saidbody and having oppositely acting pressureiiaces exposed respectively insaid chambers, means for directing fuel under pressure to said controlchamber, a restrictedfiow passage located en.-. tirely within saidbodyand independent of said last mentioned means and extending from said,control chamber to said valve chamber along said element to establish adirect constantly open in-- tercommunication between said chambers forpermitting a gradual equalization of the pressures therein, said valvechamber beingadapted to receive fuel under pressure from'said controlchamber only through said restricted passage, said element beinghydraulically operable solely in response to the varying differentialdetermined by the fuel pressures acting on said'faces, and injectionvalve means operable by said element.

8. A fuel injection nozzle comprising, in combination, a body section, acylindrical shell secured to one end of said section and defining aconfined reservoir chamber, a discharge nozzle 5 removably secured tothe other end of said section and formed with a valve chamber and acontrol chamber and with a discharge passage opening from said valvechamber, the face of said discharge tip adjacent said body section beingformed with an annular groove, passages formed in said body section andestablishing communication betweenvsaid reservoir and said groove,passages in said discharge nozzle and establishing communication betweensaid valve chamber and said groove, a pressure responsive memberreciprocable in said discharge nozzle and having oppositely acting facesexposed respectively in said chambers, the area of the face exposed insaid control chamber being at least as great as the area of the faceexposed in said valve chamber, a restricted bore extendinglongitudinally in said member and opening at opposite ends respectivelyto said valve and control chambers, and means for supplying fuel undervarying pressure to said control chamber.

9. A unitary fuel injection nozzle comprising, in combination, a bodyhaving an enlarged valve chamber, a discharge orifice opening from saidchamber, a valve seat at the inlet of said orifice, a control chamberand a bore connecting said chambers, an element reversibly slidable insaid bore solely by hydraulic pressure and having a valve member on oneend adapted to engage said valve seat and having a lifting pressure faceabout said valve member constantly and freely' exposed in said valvechamber and a seatingpressure face on the other end exposed in saidcontrol chamber and at least equal in eifective transverse area to theaggregate area of said valve member 40 and said lifting face, means forsupplying fuel under pressure to said control chamber, and meansdefining a restricted constantly open leakage passage in said bodyeflecting adirect uninterrupted intercommunication along said ele- 4ment betweensaid chambers, and affording means for the supply of fuelsolely from said control chamber directly to said valve chamber.

10. A fuel injection nozzle comprising, in combination, a body having anenlarged valve chamber, a discharge orifice opening from said chamber, avalve seat at the inlet of said orifice, a control chamber and a boreconnecting said chambers, an element reversibly slidable in said boresolely by hydraulic pressure and having a valve member on one endadapted to engage said valve seat and having a lifting pressure faceabout said valve member constantly and freely exposed in said valvechamber and a seating pressure face on the other end exposed in saidcontrol chamber and at least equal in effective transverse area to theaggregate area of said valve member and said lifting face, means forsupplying fuel under pressure to said control chamber, means defining arestricted constantly open leakage passage in said body effecting adirect uninterrupted in- .tercommunication along said element betweensaid chambers, and an enlarged storage reservoir out of directcommunication with said control chamber and in open intercommunicationwith said valve chamber independently of said leakage passage.

11. A fuel injection nozzle comprising, in combination, a body having avalve chamber with an outlet valve seat, a discharge passage openingfrom said seat, a control chamber, and a bore connecting said chambers,a plunger reciprocable in said bore and having oppositely actingpressure faces exposed respectively in said chambers, the area of thepressure face exposed in said control chamber being as large as that ofthe pressure face exposed in said valve chamber, a valve member movablewith said plunger and adapted to coact with said seat, said to define arestricted passageopening from said control chamber through said bore tosaid valve chamber, and passage means for supplying fuel under pressureto said control chamber, whereby predetermined pressure fluctuations inopposite directions in said means will cause said valve member to moverespectively into and out of engagement with said seat.

JOSEPH R. LEMON.

plunger being formed

